Apparatus for the manufacture of hollow frangible pipes

ABSTRACT

The invention is concerned with the manufacture of hollow frangible pipes and contemplates the provision of an automatic pipe-making apparatus of the packer head or roller head type, including means for adjusting the rate of lift of the packer shaft means for varying the rate of feed of the material from which the pipe is to be formed and means for relating these two variable rates in a manner such that the pipes formed thereby are uniformly packed to the optimum density throughout their length.

United States Patent Waddington May 2, 1972 [54] APPARATUS FOR THE MANUFACTURE OF HOLLOW FRANGIBLE PIPES Primary Examiner.l. Spencer Overholser Assistant Examiner-Dewalden W. Jones Attorney-Shlesinger, Arkwright & Garvey [72] Inventor: Philip Waddington, 839 Provost Drive, Ot-

tawa 10, Ontario, Canada [22] Filed: Apr. 28, 1970 211 Appl. No.: 32,693 ABSTRACT The invention is concerned with the manufacture of hollow [30] Foreign Application P iorit D 1 frangible pipes and contemplates the provision of an automatic pipe-making apparatus of the packer head or roller head May 8, 1969 Canada ..O50,59l yp including means for adjusting the rate of lift of the 52 us. Cl ..425/427 425 449 PackerShafmeaS Varying feed material [51] Int. Cl ..B2 8b 21/32 from which P is to be fol'med and means for relating 53 Field of Search ..25 36, 30 c, 30 R, l26, DIG. 8 these two variable rates in a manner Such that the P p formed thereby are uniformly packed to the optimum density [56] References Cited throughout their length.

UNITED STATES PATENTS 6 Claims, 6 Drawing Figures 3,095,628 7/1963 Norton et al ..25/36 0 A "T T 'l V 7* .A r :5

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PATENTEDMAY 2 [s72 SHEET u or e PATENTEnmAYz 1912 3,660,003 sum 5 0F 6 UNIT] FIGS WIIIV/d? w, z/M /M W M APPARATUS FOR THE MANUFACTURE OF HOLLOW FRANGIBLE PIPES This invention relates to a method and apparatus for the manufacture of hollow frangible pipes. In particular the invention is concerned with the manufacture of concrete pipes in a machine of the packer head or roller head type.

In the manufacture of pipes by machines of the packer head or roller head type a main shaft having a packer head secured to one end thereof is adapted to be moved in a vertical direction through a mould and ring assembly whilst being simultaneously and continuously rotated. The packer head is usually provided with packing elements in the form of wings or rollers and having been lowered into the mould is rotated and a concrete mix is then poured into the top of the mould so that the packer head and its packing elements force the concrete outwardly against the inner surface of the mould. The shaft and the packer head are then slowly moved upwardly through the mould whilst being rotated at a speed such that the incoming concrete mixture is packed densely against the inner surface of the mould throughout its whole length thus forming a concrete pipe. After the packing head has been raised clear of the mould the latter is removed with the green pipe therein and an empty mould is placed in position in the machine.

In the known packer head machines the rate of lift of the shaft and the associated packer head is normally a fixed rate although for a given machine several fixed rates may be provided. The rate of feed of the concrete mixture is likewise a fixed rate but is manually controlled as to stopping and starting. The density of the wall of a finished pipe is determined by the skill of the operator in feeding the right amount of concrete into the mould so that, ideally, it is sufficiently and uniformly packed throughout the length of the pipe. It will therefore be appreciated that with the prior art machines this desirable uniformity and correct density of packing is dependent on the skill of the machine operator.

The present invention relates essentially to an automatic pipe-making apparatus including means for adjusting the rate of lift of the packer shaft in a packer head or roller head type machine, means for varying the rate of feed of the concrete mixture and means for relating these two variable rates in such a way as to produce a concrete pipe in which the concrete mixture is uniformly packed to the optimum density throughout its length.

The present invention provides a hydro-mechanical control system which ensures uniform packing and consistent density through the whole length of the pipe with automatic cycling of the complete operation.

The present invention has for an object the provision of a pipe-making machine of the packer head type in which a desired uniformity and packing density of the pipe is obtained automatically without the intervention of a skilled operator and by means of which pipes of the desired characteristics may be produced on a consistent production line basis with close tolerance quality control.

In accordance with the foregoing and other objects, this invention contemplates the provision of an apparatus for the manufacture of hollow pipes comprising a mould, a shaft disposed in said mould and extending axially thereof, a packer head mounted adjacent one end of said shaft and movable therewith, and means for imparting longitudinal and rotary movement to said shaft to move the packer head through said mould whilst continuously rotating same, of the improvement which comprises a mechanism for automatically and continuously varying the rate of feed of material supplied to the apparatus and the packing density of the material being packed against the inner surface of the mould, said mechanism adapted to maintain a pre-selected relationship between the rate of feed of said material to the mould rate of longitudinal movement of the shaft and associated packer head through the mould whereby the pipe is uniformly and densely packed throughout its length.

Preferably the material feed to the apparatus is controlled by a fluid motor supplied from a fluid source through a first variable flow valve, the axial movement of said packer head dies being effected by fluid operated cylinders supplied from a second fluid source through a second variable flow valve, said first and second cylinders supplied from the or a second fluid source through a second variable flow valve, said first and second variable flow valves being mechanically interlinked whereby movement of one of said valves in one direction between its open and closed position produces a movement of the other valve in the opposite direction between its open and closed position, the relative movement of said first and second valves being adjusted to maintain a predetermined relationship between the rates of feed of material to the mould and the rate of axial movement of the packer head through the mould.

The rate of axial movement of the packer head through the mould is continuously varied in dependence on the resistance to the rotary motion of the packer head and is maintained in a predetermined relationship with the rate of feed of material to the mould. The arrangement is such that an increase in the density of packing of material in the mould by the packer head produces a decrease in the rate of feed of material to the mould and a predetermined proportional increase in the rate of axial movement of the packer head through the mould.

In a preferred form of the invention the variable flow valves are interlinked through a mechanism including a bar and first and second cams mounted in spaced relationship on said bar, said first and second cams associated with and adapted upon movement of said bar to actuate said first and second control valves respectively, said packer head adapted to impart linear motion to the bar through a fluid actuated cylinder, movement of said cylinder being proportional to the resistance offered to the rotary motion of the packer head by the material being packed against the inner surface of the mould and adapted to actuate said first and second valves simultaneously in mutually opposite directions.

The invention also resides in a method of making hollow pipes which comprises the steps of rotating a packer head within a hollow mould, feeding the moulding material into the mould above said rotating packer head, moving said rotating packer head axially within said mould and continuously varying said feeding rate and the speed of axial movement of said packer head through the mould to maintain a pre-selected relationship therebetween, whereby to produce a pipe which is uniformly and densely packed through its length.

Other features of the invention will be described hereinafter and referred to in the appended claims.

The invention will now be more particularly described with reference to the accompanying drawings, in which:

FIG. 1 is a schematic elevation view, partly in section, showing the essential elements of the pipe-making machine;

FIG. 2 is an enlarged view showing in detail the bell area of the mould with the packer head in its lowermost position within the mould;

FIG. 3 is a schematic view of the feed and packer head lift control mechanism;

FIG. 4 is a plan view, partly in section, showing details of the controller mechanism;

FIG. 5 is a sectional view in elevation of the controller mechanism in FIG. 4; and

FIG. 6 is a schematic diagram of the hydraulic control circuit.

Referring to the drawings, FIG. I shows a support frame consisting of vertical posts 2 and 4 resting at their lower ends on horizontally disposed l-beams 6 and 8 and supporting a cross member 10 at their upper ends. The inner opposed vertical walls of the posts 2 and 4 form tracks for rollers 12 mounted on opposite sides of a carriage 14 adapted to be reciprocated in a vertical plane, as shown by the arrow 16, through the agency of the lift cylinders 18 and 20. A motor 22 mounted on the upper end of the carriage 14 is arranged to rotate the head shaft 24 which carries at its free end a packer head 26. In the position shown in FIGS. 1 and 2 the packer head is in its lowermost position within the mould 28 which latter may be connected at its lower end with a vibrator unit such as that. generally designated 30. In this position concrete is fed into the mould above the packer head from a conveyor 32 driven through a motor 34 (see FIG. 6) and the concrete is compacted in the bell area 36 by a vibratory process through the agency ofa vibrator unit such as 30.

This position of the machine, i.e. with the packing; head 26 in its lower-most position and concrete being fed into the mould, may be considered the start of a pipe-making cycle. At this time the shaft 24 is being rotated by the hydraulic motor 22. The hydraulic fluid pressure in the feed line to the hydraulic motor 22 varies according to the work being done by the packer head 26, therefore it will reflect, in increasing pressure, the density of packing which is achieved by the rotary motion of the packer head. This hydraulic pressure is applied to a cylinder 40 located in a separate mechanism generally designated 42. As the concrete becomes compacted to the required density in the bell area 36 of the pipe mould and, by the packing elements, in the wall of the pipe 38 immediately above it, an increased resistance to the rotary motion of the packer head will be reflected in an increase of the hydraulic pressure applied to cylinder 40. This will result in a motion of the bar 44 due to the extension of cylinder 40 and this motor is resisted by the spring 46.

Linear motion of the bar 44 which carries a cam 48 dependent upon the contour of the cam, will result in a change in the volume of hydraulic fluid passing through the valve 50. Valve 50 is a pressure and temperature compensated variable flow control valve.

The mechanism 42 is arranged in such a manner that the increase in the hydraulic pressure applied to the motor 22, which is dependent upon the packing effort of the packer head 26, will result in an increased supply of hydraulic fluid to the lift cylinders 18 and which derive their fluid supply from a separate source through the variable valve 50. The cylinders 18 and 20, as will be appreciated, control the vertical motion of the shaft 24 and the packer head 26.

A second cam 52, also located on the bar 44, actuates a variable flow control valve 54 but in such a manner that an increase in pressure in cylinder 40 and a corresponding motion of bar 44 result in a decreased flow of hydraulic fluid through the valve 54. The flow of hydraulic fluid through valve 54 is used to actuate an hydraulic motor 56 and by this means to drive the conveyor 32 which feeds a concrete mixture into the pipe mould 28.

It will be seen that with this arrangement upon occurrence of a condition whereat the pipe wall within the mould is insufficiently compacted there results a drop in pressure supplied to the cylinder 40 which will result in both an increased flow in concrete mixture and a retardation of the upward movement of shaft 24. These two changes will result in an increase in the density of packing by the packer head 26. Similarly a condition of unduly heavy packing (also objectionable from the standpoint of a well finished concrete pipe), because of the resistance offered to the rotary motion of the packer head 26, will result in an increase in the pressure supply to the motor 22 thence the cylinder 40, which in turn will cause the bar 44 to move to the left thereby reducing the flow ofconcrete mixture to the mould and accelerating the upward motion of shaft 24. By proper adjustment of the control mechanism 42 and by establishment of the correct relationship between the rate of feed of the concrete mixture and the rate of lift of the shaft 24 (which will be achieved by adjusting the contours of the cams 48 and 52) an optimum condition will be achieved whereby the concrete pipe will be uniformly and densely packed throughout its length.

The hydraulic pressure control circuit for the apparatus is shown schematically in FIG. 6 and includes a mechanism designated P1 consisting of an electric motor 60 driving a constant delivery gear type pump 62 which actuates the hydraulic motor 22 which controls the rotation of the head shaft and the pipe packer head assembly. Similarly P2, which is a variable volume system consisting of an electric motor 64 driving a variable volume type pump 66, actuates the other machine motions, specifically the conveyor feed motor 34 and the head lift cylinders 18 and 20.

A connection is made between the input to the hydraulic motor 22 and the cylinder 40 so that cylinder 40 responds, by extending against the spring 46, to the pressure generated by the torque output of the hydraulic motor 22, which in turn depends on the packing effort exerted by the packer head 26 on the concrete within the mould 28.

The movement of cylinder 40 modifies the rate of flow of hydraulic fluid to both the lift cylinders 18 and 20 and to the hydraulic motor 34 which latter drives conveyor 32 and thus controls the concrete feed to the mould.

Valve 70 is a solenoid operated 4-way valve controlling the lift cylinders 18 and 20. When solenoid al is energized fluid flows to the cylinders but is supplied through valve 50 which more or less restricts the flow according to the depression of its cam roller 49 by cylinder 40, thus varying the rate of lift of cylinders 18 and 20.

When solenoid la! is energized valve 70 allows the fluid from the lift cylinders 18 and 20 to return to the tank under gravity from the load on the lift cylinders, and valve 50 is rendered inoperative. However, the return flow is passed through the valve 72 which enables deceleration to be applied to the rate of descent of lift cylinders 18 and 20. This is achieved by means of a mechanical cam (not shown in the drawings) operating on the valve 72.

Valve 74 is a solenoid operated two-position valve which, when open, actuates the hydraulic motor 34 which controls the conveyor 32 and hence the rate of feed of concrete to the mould. The supply of fluid to the valve 74 is metered through valve 54 which is also controlled by cylinder 40 so that the concrete feeds also is modified by the same system which modifies the rate of lift of shaft 24 and the packer head assembly 26.

What is claimed is:

1. In an apparatus for the manufacture of hollow pipes comprising a hollow mold, a shaft disposed in said mold and extending axially thereof, a packer head mounted adjacent one end of said shaft and movable therewith, and means for imparting longitudinal and rotary movement to said shaft to move the packer head through said mold whilst continuously rotating same, the improvement which comprises a mechanism for automatically and continuously varying the rate of feed of material supplied to the apparatus and the packing density of the material being packed against the inner surface of the mold, said mechanism adapted to maintain a preselected relationship between the rate of feed of said material to the mold and the rate of longitudinal movement of the shaft and associated packer head through the mold whereby the pipe is uniformly and densely packed throughout its length.

2. Apparatus as claimed in claim 1 wherein the material feed is controlled by a fluid motor supplied from a first fluid source through a first variable flow valve, the axial movement of said packer head being effected by fluid operated cylinders supplied from the or a second fluid source through a second variable flow valve, said first and second variable flow valves being mechanically interlinked whereby movement of one of said valves in one direction between its opened and closed position produces a movement of the other valve in the opposite direction between its open and closed position, the relative movement of said first and second valves being adjusted to maintain a predetermined relationship between the rates of feed of material to the mold and the rate of axial movement of the packer head through the mold.

3. Apparatus as claimed in claim 1 wherein the rate of axial movement of said packer head through said mold is continuously varied in dependence on the resistance to the rotary motion of the packer head and is maintained in a predetermined relationship with the rate of feed of material to the mold.

4. Apparatus as claimed in claim 1 wherein an increase in the density of packing of the material in the mold by the packer head produces a decrease in the rate of feed of material to the mold and a predetermined proportional increase in the rate of axial movement of the packer head through the mold.

5. Apparatus as claimed in claim 1 wherein the material feed is controlled by a fluid motor supplied from a first fluid source to a first variable flow valve, the axial movement of said packer head being effected by fluid operated cylinders supplied from a second fluid source through a second variable valve, including a bar, and first and second cams mounted in spaced relationship on said bar, said first and second cams associated with and adapted upon movement of said bar to actuate said first and second control valves respectively, said packer head adapted to impart linear motion to said bar 

1. In an apparatus for the manufacture of hollow pipes comprising a hollow mold, a shaft disposed in said mold and extending axially thereof, a packer head mounted adjacent one end of said shaft and movable therewith, and means for imparting longitudinal and rotary movement to said shaft to move the packer head through said mold whilst continuously rotating same, the improvement which comprises a mechanism for automatically and continuously varying the rate of feed of material supplied to the apparatus and the packing density of the material being packed against the inner surface of the mold, said Mechanism adapted to maintain a preselected relationship between the rate of feed of said material to the mold and the rate of longitudinal movement of the shaft and associated packer head through the mold whereby the pipe is uniformly and densely packed throughout its length.
 2. Apparatus as claimed in claim 1 wherein the material feed is controlled by a fluid motor supplied from a first fluid source through a first variable flow valve, the axial movement of said packer head being effected by fluid operated cylinders supplied from the or a second fluid source through a second variable flow valve, said first and second variable flow valves being mechanically interlinked whereby movement of one of said valves in one direction between its opened and closed position produces a movement of the other valve in the opposite direction between its open and closed position, the relative movement of said first and second valves being adjusted to maintain a predetermined relationship between the rates of feed of material to the mold and the rate of axial movement of the packer head through the mold.
 3. Apparatus as claimed in claim 1 wherein the rate of axial movement of said packer head through said mold is continuously varied in dependence on the resistance to the rotary motion of the packer head and is maintained in a predetermined relationship with the rate of feed of material to the mold.
 4. Apparatus as claimed in claim 1 wherein an increase in the density of packing of the material in the mold by the packer head produces a decrease in the rate of feed of material to the mold and a predetermined proportional increase in the rate of axial movement of the packer head through the mold.
 5. Apparatus as claimed in claim 1 wherein the material feed is controlled by a fluid motor supplied from a first fluid source to a first variable flow valve, the axial movement of said packer head being effected by fluid operated cylinders supplied from a second fluid source through a second variable valve, including a bar, and first and second cams mounted in spaced relationship on said bar, said first and second cams associated with and adapted upon movement of said bar to actuate said first and second control valves respectively, said packer head adapted to impart linear motion to said bar through a fluid actuated cylinder, movement of said cylinder being proportional to the resistance offered to the rotary motion of the packer head by the material being packed against the inner surface of the mold and adapted to actuate said first and second valves simultaneously in mutually opposite directions.
 6. Apparatus as claimed in claim 1 wherein the molding material is concrete. 